Needle roller bearings are used in a wide variety of applications. FIGS. 1 and 2 illustrate one such application, wherein the needle roller bearings are incorporated into an intermediate shaft assembly 10 for connecting a steering wheel of an automobile to a rack-and-pinion gear assembly of an automobile steering system. Referring to FIGS. 1 and 2, the intermediate shaft assembly 10 shown comprises a first yoke 12, a first spider assembly 14 rotationally coupled to first yoke 12, and a steering column clamp yoke 16 rotationally coupled to first spider 14 to form a first Cardan joint assembly. Shaft assembly 10 also includes a seal 18, a hollow tubular shaft 20, a solid shaft 22 extending from an interior of the tubular shaft, a second yoke 24 mounted to solid shaft 22, a second spider assembly 26 rotationally coupled to second yoke 24, and a gear clamp yoke 28 rotationally coupled to the second spider. The second yoke 24, second spider 26, and gear clamp yoke 28 combine to form a second Cardan joint assembly coupled to solid shaft 22.
In the shaft assembly shown in FIGS. 1 and 2, first spider 14 and second spider 26 are basically identical. Therefore, the following description of spider 26 is equally applicable to spider 14. As seen in FIG. 2, each spider 26 has a central hub 26a and a plurality of trunnions 26b extending from the hub. A needle roller bearing 30 as shown in FIG. 3 is mounted to each of trunnions 26b. As seen in FIG. 3, each needle roller bearing 30 comprises a plurality of conventional solid needle rollers 34 and a cage 36. Cage 36 may be a plastic molded type cage or a stamped sheet metal type cage that includes spaced end rings 38 and 40 that are connected by a plurality of cross bars 42 to form a plurality of roller receiving windows.
Needle rollers 34 run directly along an interior cylindrical surface (not shown) inside a hole 44 (FIG. 1) formed in yoke 24.
Needle rollers 34 also run directly along an exterior cylindrical surface (not shown) formed along each trunnion 26b of spider 26. These interior surfaces and exterior surfaces form inner and outer races for the needle rollers 34.
In existing joint assemblies of the type just described, differences in the diameters of the needle rollers mounted in a given bearing can cause a pronounced rattling of the bearing in the joint, resulting from intermittent contact between undersized needle rollers and the trunnion and/or yoke during operation of the joint. To help prevent this rattling, the diameters of the needle rollers and the diameters of the portions of the trunnions contacting the needle rollers must be held to within very tight tolerances to help ensure noise-free operation of the joint. This greatly increases the expense of the joint.